Individual stalls in public area restrooms found in schools, airports, movie theaters, stadiums, and recreation parks, etc. are generally provided by subdividing walls in the form of separate vertical bathroom partitions installed after the restroom has been finished. When one end of a bathroom partition is mounted on a traditional wall, the other end of the partition generally terminates at a stile. These partition walls may be attached by brackets or other devices to a stile in a plane perpendicular to the stile. Stiles may be used to frame doors in bathroom compartments, wherein the door is mounted in line with and between two stiles. The stiles themselves may be anchored to the floor, hung from the ceiling, or both.
FIG. 1 shows a typical layout of a partition assembly used to enclose individual restroom stalls. An exemplary stall is provided enclosed by a side panel 17 and an inward swinging door 18 attached to a stile 16 as well as by the restroom walls themselves. In an alternative embodiment, a pair of stiles 16 may be provided on either side of the door 18. The door 18 is an inward swinging door which travels through an arc of approximately 90 degrees. The door may be mounted on the stile using a hinge 14, which may be a full length spring and hinge assembly, a full length cam and hinge assembly or a short barrel cam hinge. The door 18 may be provided with a stop 19 to prevent the door 18 from swinging past the fully closed position.
Another stall is provided for handicapped access consisting of side panels 17 and an outward swinging door 15 attached to a stile 16 using a hinge 13. The front of the stall is cordoned off by the door 15 and a connector panel 9 as well as the stiles 16 on which the door 15 and connector panel 9 are mounted. Depending on the installation, the door 15 can swing through an arc up to as much as approximately 180 degrees. The door 15 may also be provided with a stop 10 to prevent the door 15 from swinging past the fully closed position.
In general, inward swinging stall doors must remain closed or partially closed even if the stall is not in use. Outward swinging stall doors such as those used in handicapped accessible stalls are required to remain completely closed if the stall is not in use for safety and other reasons. Stall doors may be kept closed when not in use by a pre-loaded force of the spring where an institutional hinge is used, or by a cam which uses the door's own weight and gravity to induce the door to rotate. The spring and hinge assembly, also known as an institutional hinge, is desirable in certain situations because its simple and sturdy construction resists vandalism and because it provides greater privacy to an occupant of a stall in which it is installed by covering the majority of the gap between a stall door and stile on the hinge side.
Restroom stall doors in heavy use areas such as airports and recreation parks may be used as much as several hundred times a day. As such, where these doors are mounted using spring and hinge assemblies, the springs should preferably be able to function for at least several hundred thousand cycles before failing and requiring replacement. Torsion spring and hinge assemblies used currently do not meet these customer goals for partitions. It is important that a reliable device be provided which causes the stall door to come to a completely closed position on its own; otherwise it can be especially difficult for a person in a wheel chair to properly latch the door as they will need to manually pull the door in to do so.
In place of a torsion spring and hinge assembly, a cam and hinge assembly or short barrel cam hinges may be used which do not incorporate springs needing periodic replacement. However, these hinges require that the stile be properly aligned and upright to function properly, and do not provide the privacy of the torsion spring and hinge assembly due to the inherent gaps 11 and 12 present between the stiles 16 and the doors 15 and 18 respectively, of the stalls.
FIG. 2 shows an exploded front view of a known torsion spring 20 installed in a spring and hinge assembly. The hinge comprises two hinge halves 25 joined by a hinge pin 28 at knuckles 24. The torsion spring 20 includes spring arms 23 and a coil body 29 having a plurality of spring coils 21. In one embodiment, the coil body 29 is provided with twenty six coils. The hinge pin 28 is provided running through the coil body 29 of the torsion spring 20. The spring arms 23 of the torsion spring 20 extend outward to bear on the hinge halves 25 to exert a pre-load force on the hinge assembly. FIG. 3 shows an end view of the institutional hinge assembly of FIG. 2 having the torsion spring 20.
FIG. 4 shows an assembled end view of the spring and hinge assembly of FIG. 3. The torsion spring 20 consists of the coil body 29, as well as spring arms 23 which extend from the ends of the coil body 29. The spring arms 23 diverge from the spring coils 21 at the reverse bends 22. The right-hand spring arm 23 shown in FIG. 4 for example transitions briefly from a counter-clockwise bend to a clockwise bend at one of the reverse bends 22 to provide a 0.05″ step s between the spring arm 23 and a line tangent to the spring coils 21 running in parallel with the spring arm 23. The reverse bends 22 are provided in order to create a pre-load force in the spring 20 when the spring is installed in a hinge assembly mounted on a stile. The reverse bends 22 also allow the spring arms 23 sufficient clearance from the hinge halves 25 to bear at least in part on the top surfaces of the hinge halves 25 rather than entirely against their edges, as would be the case with the embodiment shown were the reverse bends 22 not present.
Despite the reverse bend being a widespread feature among torsion springs in the art, it is especially common for these springs to fail under normal use at the location of the reverse bends that join the spring arms to the spring coils. A load placed on the spring arms 23 and counteracted by a reaction force induced in the coil body 29 will naturally tend to concentrate at the place where the spring arms 23 meet the coil body 29, placing a reverse tension on the material of the reverse bends 22 prior to transferring to the coil body 29 of the spring 20. Compounding this problem are the preexisting internal stresses in the material of the spring 20 in the vicinity of the reverse bends 22 caused by the creation of the reverse bends 22. Finally, there is the remaining wear as the spring 20 flexes the spring arms 23 against the edges of the hinge halves 25.
The confluence of these factors has a deleterious effect on the longevity of known torsion springs, and commonly causes them to fail in the area of the reverse bend in an unacceptably short time. The reliability of known torsion springs is much worse when used with a hinge on a door which opens to an angle greater than 90 degrees, as is often the case with stalls having outward swinging door designs. These failures lead to customer complaints due to toilet partition doors that remain in an open position but are required to be closed. Were a solution to this problem to be found, it would improve reliability and customer satisfaction as well as reduce the costs associated with field replacements of damaged spring and hinge assemblies, stocking and handling replacement spring and hinge assemblies.